The soleplate of a conventional electric iron is usually heated by an electric resistance heater which is mounted inside a housing. The resistance heater includes one or more wire-like resistors which can be connected to an electric power source whereby the resistors generate heat to heat up the soleplate. The resistance heater is installed on the soleplate. Such electric iron is rather complicated in construction. The cost of manufacturing and assembly of the electric resistance heater is rather high, especially since it has to be mounted on a support made of an electrically insulating material.
Furthermore, it takes a relatively long period of time to heat an electric resistance heater until it begins to generate heat at the desired rate, and it takes a relatively long period of time to ensure that an electric resistance heater is adequately cooled upon completion of an ironing operation. Thus, large quantities of heat energy are lost during heating and cooling of the soleplate.
A conventional soleplate can be made of a single piece of metal such as aluminum or steel. An advantage of aluminum is that its heat conductivity is quite satisfactory and that it is relatively light in weight. However, the ability of an aluminum soleplate to resist scratching, scoring and similar damage is unsatisfactory. A soleplate which is made of steel is more resistant to wear and scratching. However, it is rather heavy in weight and its thermal conductivity is not satisfactory.
Another kind of soleplate is formed of two pieces made of different materials. There is a core portion which is electrically heatable and is made of aluminum. It carries a thin-walled base plate of steel which comes in actual contact with the clothing to be ironed. This kind of soleplate is complicated in structure and increases the cost of the soleplate and of the entire iron.
Conventional heating elements of electric irons are often of high electrical resistance. Electrical current is hence low under direct current electrical power and incapable of generating sufficient energy uniformly over an area for heating.
Therefore, there is a need to provide an improved electric iron that is simple in construction, less costly to manufacture, light in weight, capable of using direct current electrical power or batteries, and high in heating efficiency.
The above description of the background is provided to aid in understanding the heating element and the electric iron disclosed in the present application, but is not admitted to describe or constitute pertinent prior art to the heating element and the electric iron disclosed in the present application, or consider any document cited herein as material to the patentability of the claims of the present application.